<p>This study examines the effects of alternating raster angles on the mechanical properties and fracture modes of specimens fabricated by material extrusion additive manufacturing. Specimens with different raster angles [+ 0°/-90°], [+ 45°/-45°], [-45°/ + 45°], and [+ 30°/-60°] were manufactured, followed by tensile tests. Digital Image Correlation (DIC) quantified strain field evolution and Poisson's ratio, while scanning electron microscopy (SEM) and numerical imaging analyzed fracture mechanisms. Experimental results revealed that PLA samples exhibited significant anisotropy. Specimens with a raster angle of [+ 30°/-60°] showed a high tensile strength and a low elongation at break compared to other orientations. DIC analysis of tension-loaded PLA specimens shows distinctive strain field patterns highly dependent on raster orientation. Furthermore, raster angle shows a significant effect on poisson’s ratio υ. As raster orientations shift from [+ 0°/-90°] to [-45°/ + 45°], υ increases from approximately 0.19 to 0.3. Moreover, the fracture mechanisms, displaying both inter- and intra-layer characteristics, are influenced by the raster orientation. A numerical analysis was conducted across the four raster angle combinations evaluated experimentally ([+ 0°/ − 90°], [+ 45°/ − 45°], [− 45°/ + 45°], and [+ 30°/ − 60°]). Based on these results, a polynomial mathematical model was formulated to predict Young's modulus (E) and ultimate tensile strength (R_m) as functions of raster orientation, within the bounds of the investigated manufacturing conditions.</p>